The present invention relates to producing catalytic converters. More particularly, the invention relates to producing catalytic converters, the housing or canister of which is sized down onto endplates.
Catalytic converters have been employed to catalyze exhaust gasses in vehicles for more than twenty years and have been manufactured in a number of ways. Catalytic converters play a critical role in ensuring that fuel rich gasses are converted down to acceptable levels, and not coincidentally, they are a comparatively expensive article within an exhaust system. The materials are expensive, and manufacture is labor intensive. Furthermore, design packages that increase durability and improve overall system performance for reductions in emissions are at a premium. Accordingly, methods of manufacture have been put forth in attempts to reduce manufacturing costs, while at the same time, increase durability and stabilize system performance.
One method of manufacturing catalytic converters is to provide a pre-made canister and stuff it with the catalyst substrate and the insulation/support pad. In this method the catalyst substrate is wrapped with an intumescent mat of a selected thickness and weight (various weights are employed for various applications and desired properties). Commonly, the wrapped substrate material will create an assembly having outer dimensions that measure about 8 mm larger than the inside dimensions of the converter shell or canister. The assembly as described is then forced through a reduction cone and into the converter shell. Up to 20,000 lbs. of pressure can be required to accomplish the insertion of the assembly into the can. The method is costly.
A commonly preferred method for producing a catalytic converter is known as xe2x80x9cthe tourniquet methodxe2x80x9d. The tourniquet method dispenses with the reducing cone and thus avoids the high insertion pressures on the substrate and mat materials. The method places the substrate and mat assembly into a canister open on one longitudinal edge. The canister is closed around the assembly by straps and compressed to the desired size. The open ends of the canister will, in this position, be overlapping and then are welded together. This method is also expensive and labor intensive. Further, due to this overlap, engineering design consideration must be given to the space alteration inside the canister due to the overlapped edge. The overlapped edge causes a mat density change in the local area of the overlap. This is a further cost addition.
U.S. Pat. No. 4,969,264 to Dryer et al. further describes a conventional catalytic converter with a reduced central housing section that compresses a support mat around a substrate. This method utilizes end bushings securely affixed to the housing body. Such converters are also expensive and labor intensive in manufacture.
Accordingly, there remains a need in the art for a catalytic converter that is easily and inexpensively manufactured, that increases durability, stabilizes system performance, and does not restrict design choice.
The drawbacks and disadvantages of the prior art are overcome by the catalytic converter of the present invention and its method of manufacture, the catalytic converter comprising: a catalyst; a first endplate, having an annular ring positioned around a portion of a first annular end of said catalyst; a second endplate, having an annular ring positioned around a portion of the second annular end of said catalyst; a mat support, covering said catalyst and the annular rings of said endplates; and a shell, covering and in close contact with the combined catalyst, mat support, and endplates.
The catalytic converter of the present invention is constructed by the method comprising: providing a first endplate having an annular ring; providing a second endplate having an annular ring; providing a catalyst; positioning the annular rings of said first and second endplates over each of the annular ends of said catalyst; covering said catalyst and the annular rings of said first and second endplates with a mat support; providing over said mat support and said endplates an oversized shell; and sizing down said oversized shell over said mat support and said endplates such that the shell is in close contact with said mat support and said endplates.
The above-described and other features and advantages of the present invention will be appreciated and understood by those skilled in the art from the following detailed description, drawings, and appended claims.